LOCKPORT – Memories of a long-forgotten city dump, which now will cost the state millions of dollars, will be stirred at a public meeting Thursday in City Hall.

A $10.5 million remediation plan for a remote area of west Lockport called “the Gulf,” where tons of incinerator ash were dumped decades ago, will be discussed at the 6:30 p.m. session.

The state Department of Environmental Conservation says that although the city once operated a municipal landfill in the area – and the ash seems to have come primarily from household waste – there is no documentary proof that the city dumped the ash in the ravine.

“We haven’t identified a responsible party yet, because we don’t have any records that show who disposed of it. And the land that it’s on is not entirely city property. It’s on city property, town property, NYSEG property, Somerset Railroad property and two other residential properties that extend into the gorge,” DEC project manager Greg Sutton said.

Because of that, Sutton said in an interview last week, the DEC is unable to stick the city with the cleanup tab.

The state Superfund will carry the cost, although Sutton said the DEC will refer the matter to the State Attorney General’s Office to see if it can prove the involvement of any responsible parties.

Mayor Michael W. Tucker was pleased to hear that the city won’t have to pay, but he said he hadn’t received any information about the DEC’s cleanup plan beyond the publicly issued fact sheet.

“Nobody’s contacted me about it,” said Norman D. Allen, city director of engineering and public works.

He said that when the DEC was investigating the site, “They called me to find out where the sanitary [sewer] line was.”

He was referring to a major sewer main called the “Gulf interceptor,” which carries sewage from the southwest part of the city through the Gulf area to the city’s sewage treatment plant.

The Gulf, a steep ravine, contains a small stream that is a tributary of Eighteen Mile Creek, Sutton said.

Allen said none of the waste interferes with the operation of the sewer main. But he conceded, “They haven’t told me exactly where they’re excavating.”

The DEC’s official name for the location is the Old Upper Mountain Road Site. It covers about seven acres.

The old city dump, operated from 1921 into the 1950s, is divided into two parts by the Somerset Railroad tracks. The contaminated ash, 200,000 cubic yards of it, is to be found in what the DEC has dubbed Operable Unit 1, which is six acres north of the tracks.

“It looks like typical municipal incinerator ash,” Sutton said. “You have bottles, clay pieces and leather pieces, things that wouldn’t combust under a normal low-temperature incinerator … We didn’t find any industrial waste, we didn’t find any drums.”

Since August 2008, the Gulf has been listed by the DEC as a Class 2 site, which is an inactive hazardous waste site posing a significant threat to public health or the environment.

Officials said there are two reasons for that listing. One is elevated lead levels.

The other, said Sutton, is “a lot of evidence of people trespassing on the site and either dumping garbage there, or people digging for bottles, so they could come in contact with waste.”

Operable Unit 2, along Gulf Creek, contains contaminated sediment that spilled out of the creek onto the shores of the stream during high water periods over the decades. The sediment, whose primary contaminant is lead, was polluted by runoff from the heap of ash in the ravine, which ranges from six inches to 78 feet thick.

The DEC’s plan is to stuff as much of the ash as possible into the bottom of the ravine to create a slope which will be stable enough to support a cap.

“It was basically dumped over a cliff, so you have to have sufficient grade to be able to cap the material. Otherwise you’ll get too much erosion,” Sutton said.

After that, 18,100 cubic yards of creek sediment will be excavated, dewatered on the site and placed in the ravine atop the ash. Then the whole pile will be covered with a multi-layer cap, and an environmental easement will be placed on the land to control future use.

The ash dumping is believed to have occurred over several decades, but records are lacking as to whether the City of Lockport ever operated an incinerator.

“Maybe it was even burned at the landfill itself. They used to do that. They’d set the trash the piles on fire, which we’d never do today,” Sutton said.

The ash slid down through the gully and contaminated the wetlands and the creek below.

“The big problem down there was, they had a number of beaver dams. They would back up the water and then it would spill over the banks of the creek and contaminate the area right next to the creek,” Sutton said.

A public comment period lasts until March 28, and then the DEC will issue a “record of decision” on what it intends to do. The design of the cleanup work is expected this year, but the remedial work isn’t expected to start in late 2014 or early 2015, Sutton said.

DEC spokeswoman Kristen Davidson said the work will last about nine months and could extend over parts of two construction seasons, depending on how the dates fall.